The invention relates to laser devices and more particularly to laser devices with improved optical resonators.
Laser devices utilize a lasing medium and some means for pumping energy into the medium to produce an electron population inversion that initiates the lasing action. To propagate a laser beam and to control super-radiant lasing, the medium is arranged in an optical cavity or light path of the resonator so that the photon or light beams produced along the path through the medium are propagated back and forth between the terminal ends of the cavity. This propagation causes the laser beam to grow in magnitude with each traverse of the cavity.
The terminal ends of the cavity are conventionally formed and defined by a pair of optically reflective mirror components. These components must be critically aligned at each end of the cavity so as to reflect the incident light 180.degree., and thus back along the path of incidence at each reflective surface. In many cases the cavity or light path for the beam is linear and the mirror components are aligned and arranged at the opposite ends of the linear light path with the lasing medium being arranged along the light path between the optical reflectors. This arrangement necessitates a space separation of the reflective components and the provision of a rigid frame or comparable structure on which the reflectors must be securely mounted and properly aligned. Such structures expand and contract with temperature changes and are subject to various physical disturbances, the problems of maintaining alignment being recognized in the art. The solutions to date, however, have entailed the use of complicated and expensive equipment to facilitate the adjustments needed to attain and maintain proper alignment of the cavity terminating components.
To conserve space and/or overcome reflector misalignments caused by physical disturbances, the art has resorted, in some applications, to the use of optical resonators that provide for the lateral translation of the beam between the path through the lasing medium and one which is parallel and laterally offset therefrom. Under some circumstances, the terminating mirrors of the resonator are two separate components that are proximally located and thus subject to similar environmental conditions that tend at least to minimize disturbances arising from temperature differences. The need for special mountings to obtain proper alignment still prevails, however, because of the use of separate reflective components at the end terminals of the cavity which must be individually aligned to accomplish their intended function. There is, accordingly, a need for improved optical resonators which avoid or minimize such alignment problems.